The making of a multilayer printed circuit board involves a number of process steps one of which is the making of a glass master which is used to expose the pattern of circuit lines and lands on the circuit board. The glass master is made by taking a photosensitized glass plate and moving it in the X and Y directions under an optical exposure head of a data controlled photo tracing machine to trace the circuit pattern on the glass plate which will correspond to the circuit pattern desired on a particular circuit board which is being processed through the production line in substantial quantity. In a multilayer board, each internal circuit plane requires its own related glass master.
It becomes necessary from time to time to modify or change the circuit patterns on the internal circuit plane of a board. Heretofore, two methods have been used to accomplish this. One method was to destroy the old glass master and make a complete new glass master. This proved to be time consuming and costly. It takes about 40 hours to process a photosensitized glass plate through the photo tracing machine. Also, there is generally a waiting period in order to obtain access to the machine which is costly in the loss of production time. The other method was to change the electrical connector in the plated through holes of the board. This connector currently takes the form of the one shown in U.S. Pat. No. 3,915,537. To make a change, this connector had to be removed, the plate hole drilled and an insulating sleeve inserted. Then, a similar connector was inserted having a longer tail which had to be wire bonded externally to a circuit land. This method was costly and presented problems.